Stair climbing provides a cost-effective way of integrating physical activity into people’s everyday routines. Every multi-story building contains stairs, and people can use stairs without special equipment or changing clothes. However, voluntary stair use varies greatly. This study will develop tools and techniques that will help explain stair use by measuring various aspects of the physical environment such as “convenience” and “visibility.” The aim is to develop a way to predict stair use and a strategy for incorporating these findings into architectural design, renovation, development, and regulation.